Technical Field
The present invention relates to a method for preserving and conditioning beef by combining essential oil and modified atmosphere packaging, particularly to an optimized proportion of composite plant essential oil and modified atmosphere which is a key technology for realizing the method, and belongs to the technical field of preservation.
Related Art
Beef is rich in nutrition and high in water content, but is extremely subjected to deterioration, color change and taste change after being affected by aspects of biological, chemical and physical factors in a storage, circulating and selling process, its edible value and commercial value are severely affected, and a shelf life is reduced. Modified atmosphere packaging is to adopt composite gas (O2, N2, CO2 and the like) to replace the air in a packaging box or bag, to achieve the aim of inhibiting bacteria (microorganism) growth and propagation, thus prolonging the shelf life. CO2 gas can inhibit growth and propagation of most putrefying bacteria and mould; O2 can inhibit growth and propagation of most anaerobic bacteria, keep fresh meat color and maintain fresh fruit and vegetable to perform aerobic respiration; N2 can serve as filling gas, and does not react with the meat; plant essential oil has better anti-bacteria and killing activity and anti-free radical oxidation effect, can serve as a natural food preservative and antiseptic, has volatility and can serve as special gas.
Reasonable modified atmosphere packaging can ensure hygienic quality of a meat product and prolong the shelf life and can also generate good effect for light sensing quality of the meat product. YANG Shengsheng invented “a meat modified atmosphere preservation method”, in which 30% CO2 and 70% O2 are adopted for modified atmosphere packaging, storage is performed at 4-8° C. and a meat preserving effect is good (CN101356935A). WANG Zhiqin et al. invented “a modified atmosphere packaging beef low temperature preservation method”, which indicates that an optimal modified atmosphere proportion is 50% O2+25% CO2+25% N2 and 55% O2+35% CO2+10% N2, and can achieve a preservation effect of 24 d (CN101889601A). David, J. Warburton considered that when the CO2 concentration in the mixed gas is larger than 20%, the growth speed of aerobic bacteria is reduced by one time. The 100% CO2 modified atmosphere packaging has the best antiseptic effect but the worst meat color; and 75% O2 and 25% CO2 modified atmosphere packaging has the best meat color but the worst antiseptic effect and a short shelf life. WANG Yonggang et al. researched “optimization of modified atmosphere packaging gas ratio for cold fresh mutton”, in which the optimal modified atmosphere preservation gas ratio of 75% CO2, 10% O2 and 15% N2 is selected and can keep the cold fresh mutton at second level freshness within 18 d. FU Li et al. researched “the research of modified atmosphere packaging on preservation and color protection of cold and fresh pork”, indicating that the optimal modified atmosphere packaging mixed gas ratio for the chilled pork is 50% CO2 and 40% O2 and 10% N2 which can greatly prolong the shelf life of chilled meat in spite of the darker meat color, the aerobic bacterial count is 5.3 lgcfu/g during storage of 21 d, and in addition, a mixed gas with the proportion of 30% CO2, 60% O2 and 10% N2 can keep the meat color fresh red within 14 d. XIE Jing et al. researched “preservation effect for chilled meat by combining modified atmosphere of oxygen of different proportions with ice temperature”, and adopted 20% CO2+80% O2, 20% CO2+20% O2+60% N2 and 20% CO2+80% N2 to research the effect of modified atmosphere with oxygen of different proportions on the chilled pork at an ice temperature, a result indicates that the modified atmosphere packaging with both 80% O2 and 20% O2 can maintain the color of the chilled meat long term and better inhibit the propagation of microorganism, has a hygienic standard exceeding that of the chilled meat if the storage is over 24 d, the difference is not obvious but the advantages in the aspects of juice loss rate and water retention are achieved. Research proves that a mixed gas consisting of 50% O2, 25% CO2 and 25% N2 can keep the meat color red fresh, achieves antiseptic and preservation effects and prevents the collapsing phenomenon of the package caused by the concentration change of CO2, and the meat is preserved for 7-10 d under the refrigeration requirement of 0-4° C. Therefore, overhigh concentration O2 and CO2 modified atmosphere packaging is not favorable for the preservation of fresh meat. In conclusion, high concentration oxygen modified atmosphere has better color of fresh meat but poor antiseptic effect, high concentration carbon dioxide smodified atmosphere has poor color of fresh meat, therefore the invention concepts and designs an oxygen, carbon dioxide and nitrogen multielement modified atmosphere proportion solution which synthesizes the change rules of the sensory properties, physicochemical properties and bacterium phases of the beef during storage, determines various indexes of the beef quality and explores gas proportion components with the optimal beef preserving effect.
Plant essential oil is the important secondary metabolite of plants, consists of simple compounds with smaller molecular weights and has certain aromatic flavor. In recent years, the natural plant essential oil replacing the chemical synthetic substance as the food preservative becomes a research hot spot, and the plant essential oil contains multiple low molecular antiseptic substances and antioxidation components, and has been widely used for food preservation in many nations and regions as a natural non-toxic food antiseptic bacteriostatic agent. LIU Xiaoli et al. researched “inhibition action of composite spice essential oil to single-core proliferative listeria in pork”, which indicates that clove, cinnamon and black pepper essential oil have higher inhibition action on single-core proliferative listeria, the essential oil generate an additive action by compounding, so that the antibacterial effect of the composite essential oil is enhanced, in addition, in the research “application of composite spice essential oil in preservation of chilled pork”, a preservative compounded by 0.5% clove+0.5% cinnamon+0.5% black pepper essential oil has better preservation effect for the pork, and the shelf life of the chilled pork can be prolonged to 15 d in combination with vacuum packaging and (4+/−1)° C. storage. The result of “antimicrobial activity of illicium verum essential oil and application research thereof to meat preservation” of CHEN Qi et al. indicates that the illicium verum essential oil has certain inhibition action to escherichia coli, saccharomycetes and rhizopus oryzae and can keep the freshness of the meat. The result of “research of preservation effect of cinnamon essential oil and clove essential oil to preservation effect of chilled pork” of YAO Chengqiang et al. indicates that a composite preservative prepared from 0.8% cinnamon essential oil and 0.8% clove essential oil has the best preservation effect for the pork in combination with the low temperature (3.0+/−0.5)° C. storage. JIANG Jiefang et al. used pepper essential oil extracted by supercritical CO2 to process pork, the pork is stored at 0-4° C. in combination with vacuum packaging, the growth of spoilage microorganisms of the meat is effectively inhibited, the shelf life of the chilled pork is prolonged, and the preservation effect is improved along with the increase of the concentration of the pepper essential oil. The research “bacteriostat and preservation effect of cumin essential oil for chilled meat” of Haili Binuer indicated that the inhibition rate of the cumin essential oil for zoospores released from phytophthora capsici sporangiums is 96.64%, and the cumin essential oil has a bacteriostat and preservation effect, and can prolong the freshness of the meat. LIU Lin et al researched the preservation effect of six kinds of spice essential oil of clove essential oil, cinnamon essential oil, pericarpium citri reticulatae essential oil, garlic essential oil, anise essential oil and mustard essential oil to conditioned chicken meat and the result indicates that the clove essential oil, cinnamon essential oil and mustard essential oil have the best preservation effect, in addition, by compounding 0.03% clove essential oil, 0.09% cinnamon essential oil and 0.06% mustard essential oil, the shelf life of fresh conditioned chicken meat stored at (4+/−1)° C. can be prolonged to 21 d. GU Renyong et al. researched the preservation effect of a composite preservative prepared by four kinds of spice essential oil of clove, cinnamon, fruit of cubeb litsea tree and majoram to the pork, the result indicates that the composite preservative containing 9% cinnamon essential oil+9% fruit of cubeb litsea tree essential oil+9% majoram essential oil can prolong the shelf life of the refrigerated pork in combination with vacuum packaging in a case of storage under 0-4° C. In conclusion, the clove essential oil, illicium verum essential oil and cinnamon essential oil have strong bacteriostat effect and obvious fresh meat preservation effect, but if the plant essential oil is used for preserving the fresh meat singly, the use level is larger and the aromatic flavor is thicker. The invention combines the synergistic effect of antibacterial activity and antioxidation of the composite plant essential oil, adopts lower-concentration composite plant essential oil and lower oxygen concentration to inhibit microorganism growth and maintain color of fresh meat stable, and volatile aromatic substances of the plant essential oil serve as the specific gas components for modified atmosphere preservation.
In the research “bacteriostatic activity research of lotus leaf essential oil cooperated with modified atmosphere packaging to fresh meat” of ZHANG Yunbin et al., the lotus leaf essential oil of different concentrations is combined with high oxygen modified atmosphere packaging (80% O2, 20% CO2) and low oxygen modified atmosphere packaging (20% O2, 50% CO2, 30% N2) to perform bacteriostatic test on the escherichia coli, staphylococcus aureus and salmonella in meat, the result shows that the antibacterial effect of 2.0% lotus leaf essential oil combined with low oxygen modified atmosphere packaging is better than that of 2.0% lotus leaf essential oil combined with high oxygen modified atmosphere packaging, but fresh color of the meat cannot be kept. But this research only aims at the bacteriostatic activity of synergic preservation of the lotus leaf essential oil with 80% high oxygen modified atmosphere and 20% low oxygen modified atmosphere to the escherichia coli, staphylococcus aureus and salmonella in the fresh meat and does not synthesize the sensory properties, elasticity and other physicochemical indexes of the fresh meat for research and analysis, while after pretreatment of the composite essential oil, the present invention combines the modified atmosphere packaging for preservation and synthesizes the bacteria phase change, physicochemical indexes and sensory properties of the fresh meat to explore the optimal composite essential components and modified atmosphere proportion, and achieve the design requirements.